2007-01-27 04:22:02 · 4 answers · asked by Bruno S 3 in Science & Mathematics ➔ Mathematics
no.
Generally speaking a line on a cartesian coordinate system does not have starts and ends.
There are applications in statistics that does "best fit" that has to have a start at x=0 but not necessarily at y=0.
2007-01-27 04:26:54 · answer #1 · answered by Shorty 2 · 1⤊ 1⤋
NO it does not have to start at the origin. Remember the general y=mx +b where slope can be positive and negative and the y intercept can be anything? Say y intercept is 10, then it is not at the origin. And for example you are determining the line of best fit for the increase of temperature of heating a substance from 10 C to 100 C, then your starting point is at 10 C, not zero at the origin.
Your graph if off the origin upwards by 10. And of course if your slope is negative, you can see that you can cross the x axis either +4, +10, -2 or at the origin. It does not have to be at the origin always.
Do not force your data or graph to pass the origin if your data and calculation say otherwise.
2007-01-27 04:35:53 · answer #2 · answered by Aldo 5 · 0⤊ 0⤋
no.. because what if there were one point near the origin and all others were far away. then a line of best fit going thru the origin wouldnt be the one of best fit.
2007-01-27 04:27:11 · answer #3 · answered by johnnie_099 2 · 0⤊ 0⤋
Not at all.
Least-square regression lines (best-fit lines) are often given using y = ax+b, where b is the y-intercept. (b is calculated as mean(y)-a*mean(x), where a = r(Sy)/(Sx), r is the correlation coefficient, Sy and Sx are the standard deviations of y and x, respectively. )
2007-01-27 04:30:51 · answer #4 · answered by J 2 · 0⤊ 0⤋